1. Field of the Invention
The present invention generally relates to anti-decoupling arrangements for connectors of the type in which coupling is achieved by means of a coupling nut, and more particularly to an anti-decoupling arrangement for an electrical connector that uses a ratchet mechanism to limit rotation of the coupling nut in the decoupling direction and a spiral lock clutch to permit free rotation of the coupling nut in the coupling direction. Still more particularly, the invention relates to improvements on the anti-decoupling arrangement disclosed in commonly assigned U.S. Pat. No. 4,536,048.
2. Description of the Related Art
A typical connector to which the present invention may be applied includes a connector shell containing electrical contacts and an internally threaded coupling nut rotatably mounted on the connector shell. The connector shell is coupled to a corresponding externally threaded mating connector by means of the coupling nut in such a manner that electrical contacts in the mating connector engage the electrical contacts in the connector shell. The coupling nut is held on the connector shell by one or more snap rings and/or spring washers that are designed to captivate or press a radial flange of the coupling nut against a corresponding flange or shoulder on the connector shell.
Because the frictional anti-locking force generated by engagement between the coupling nut and connector shell in such an arrangement is insufficient to prevent the coupling nut from rotating in a decoupling direction as a result of vibrations or shocks, compromising seals and possibly affecting the integrity of the electrical connections between contacts, it is conventional to include an additional anti-decoupling mechanism in connectors likely to be used in environments where vibrations or shocks are likely to occur, such as in military high-performance aircraft and other vehicles. The simplest and most common method of preventing unintended decoupling as a result of shocks or vibrations has been to include in the connector a metal ratchet spring having protrusions or dimples at the center of the beam the ratchet spring being permanently attached to the inside diameter of the threaded coupling nut. The connector shell is provided with ratchet teeth on its outer diameter, which are engaged by the ratchet spring.
One problem with this type of coupling is that the discrete detent positions do not necessarily lie in phase with the fully clamped position of the ring, such that even slight vibrations can cause the ring to back off slightly, which can cause sealing problems. In addition, the detent members in this configuration have very little effective surface area, causing rapid wearing away of the teeth on the ratchet wheel each time the connector is mated or unmated.
A solution to the problems of wear and phasing of the ratchet teeth and detents is proposed in commonly assigned U.S. Pat. No. 4,536,048. As illustrated in FIG. 1, appended hereto, the anti-decoupling arrangement disclosed in this patent utilizes a spiral lock clutch 1 having a single axially extending spring tine 2 arranged to engage a ratchet wheel 3 positioned at the rear of the coupling nut 4, the coupling nut being captured between the spiral lock clutch 1 and a flange or shoulder 5 on a plug connector shell 6 and arranged to be threaded onto an externally threaded mating receptacle 7. The spiral lock clutch is arranged to unwind in response to turning of the nut in a coupling direction, thereby permitting the clutch to move freely in response to tightening of the nut so as to minimize the locking torque and consequently wear on the anti-decoupling mechanism. On the other hand, application of a torque to the ratchet in the opposite or uncoupling direction causes the clutch to engage the shell and lock the spring tine 2 relative to the plug connector shell 6, preventing rotation and therefore accidental loosening. When a higher torque is applied, the spring tine is able to ratchet over the teeth, thereby permitting rotation of the coupling nut in the decoupling direction.
While the use of a single beam and an integral ratchet wheel provides advantages with respect to wear and ease of operation, the single detent is subject to failure at a relatively low torque and, in addition, the integral coupling nut and ratchet wheel is difficult to manufacture.
The present invention, on the other hand, offers various improvements to the decoupling mechanism described in U.S. Pat. No. 4,536,048, including a higher and more easily adjusted decoupling torque, and greater reliability than can be provided by the single detent inherent in the use of the lateral detent and spring lock clutch design disclosed in U.S. Pat. No. 4,536,048.